The attacker, Richard Plotts, is a convicted felon, which bans him from legally owning a gun. But Pennsylvania's universal background check law did not stop him. Neither did the hospital's signs banning guns.

The proposed federal law on expanded background checks that President Obama continually pushes is similar to Pennsylvania's and would not have stopped Plotts either. Indeed, it is hard to see how it would have stopped any of the other mass shootings during his presidency.

At Mercy Fitzgerald, caseworker Theresa Hunt was killed when Plotts opened fire during a regularly scheduled appointment with Dr. Lee Silverman. Fortunately, the doctor had his own gun and returned fire, hitting Plotts three times and critically wounding him.

After firing all the bullets in his gun, Plotts still had 39 bullets on him, bullets that he could have used to shoot many other people. Silverman's three hits, however, made it possible for two other hospital employees to tackle the wounded attacker and secure his .32-caliber revolver. Plotts has since been charged with murder and attempted murder.

Yeadon Police Chief Donald Molineux was clear: "Without a doubt, I believe the doctor saved lives. ... Without that firearm, this guy [Plotts] could have went out in the hallway and just walked down the offices until he ran out of ammunition." . . .